What are Money Markets and money market instruments?

Money markets allow banks to manage their liquidity as well as provide the central bank means to conduct monetary policy. Money markets are markets for debt instruments with a maturity up to one year.
The most active part of the money market is the call money market (i.e. market for overnight and term money between banks and institutions) and the market for repo transactions. The former is in the form of loans and the latter are sale and buyback agreements - both are obviously not traded. The main traded instruments are commercial papers (CPs), certificates of deposit (CDs) and treasury bills (T-Bills).